Synthetic sponges for washing or cleaning purposes are formed of foamed synthetic or cellulose resins, such as polyurethane foams, and are widely used for scrubbing and cleaning and to hold water and soap emulsions or detergents in their open cells. Such sponges wear relatively rapidly and are easily broken or torn, because suitable foamed material having thin and weak connections between open cells is not very strong or durable. Increasing the strength of synthetic sponges has been attempted by varying the foamed composition and the dimensions of the open cells. Wear problems remain, however, and the best prior art sponges deteriorate rapidly within a few months of use, especially when used for scrubbing or scouring.
As another example of prior art sponge problems, paint rollers made of foamed material deteriorate after a few weeks of use from the stresses produced by the viscosity of the paint held in the cells of the sponge material.
Also known in the art are fibrous abrasive cloths used as scrubbing or scouring pads that are relatively durable, but do not have sponge characteristics. They cannot absorb and retain water or detergents or soap emulsions, and do not afford a spongy and yielding mass. Fiber cloths and sponges have been combined by securing a fiber cloth to one face surface of a sponge. The sponge then absorbs and holds water and cleaning materials, and the fiber cloth provides an abrasive scouring pad, but each has an independently useful life.
The invention involves recogntion of the problems of prior art sponges, fiber cloths, and other cleaning and scouring devices and an appreciation of a way of substantially improving on these devices to produce a sponge that is durable and has an abrasive capacity combined with dimensional stability, resistance to deflocculation, and resistance to wear, tears, and cuts. The invention aims at an integral and composite sponge body having both absorbent and abrasive characteristics throughout practically its entire volume and being durable and wear resistant throughout its body. The invention also aims at economy and functional effectiveness in a sponge that is stronger and more wear resistant and also has more abrasive scouring surfaces.